In response to Notice Number (NOT-OD-10-032) NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications (R01, R03, R15, R21, R21/R33, and R37) through the NIH Basic Behavioral and Social Science Opportunity Network (OppNet) we propose a significant new aim to the ongoing grant. The purpose of this new aim will be to rigorously assess the utility of pediatric functional near-infrared spectroscopy/tomography (fNIRS) methodology for the field of development social neuroscience, and to directly compare it to pediatric functional magnetic resonance imaging (fMRI). The development of brain mechanisms underlying adaptive social skills is key to the health and well-being of individuals, and to the society to which they belong. However, fMRI, our current best technology, has limitations that preclude many children from research, or contribute to unwillingness in parents to allow their child to participate. fNIRS addresses some of these limitations. We plan to directly compare fNIRS data collected using experiments currently being carried out with children in fMRI. This effort will provide a comprehensive and direct comparison of the fNIRS methodology for the study of social behaviors and processes. Demonstrating that fNIRS imaging data are extensible to the field of developmental social neuroscience would make possible a rapid advancement in a number of new research areas, including the study of populations that are currently inaccessible. Increasing the depth and breadth of the pool of potential research participants will speed scientific progress toward understanding the emergence of mental illness, the pathogenesis of psychiatric disorders that affect social cognition and social behavior (e.g., autism, anxiety disorders, anorexia, and schizophrenia) and will strongly benefit the study of the normative development of the social brain. PUBLIC HEALTH RELEVANCE: We plan to directly compare brain mechanisms for social behaviors and social processing using two imaging methodologies: magnetic resonance imaging and near-infrared spectroscopy. The former is state-of-the-art, but is has limitations that hinder the scientific study of children, while the latter is unproven in the field of pediatric neuroscience. A successful demonstration of the usefulness of fNIRS would open new lines of research into how children's brains develop to function in a social world.